1. Field of the Invention
The present invention relates to an ink jet printer that performs printing by discharging ink droplets.
2. Description of the Related Art
An ink jet printer is provided with an ink jet head. A normal ink jet head has a passage unit and an actuator. The passage unit comprises a nozzle, a pressure chamber, and an ink passage located between the nozzle and the pressure chamber. The nozzle discharges ink droplets. The actuator applies pressure (discharging energy) to the ink within the pressure chamber by changing the volume of the pressure chamber. A normal actuator comprises a first electrode, a second electrode to which a reference potential is to be applied, and a piezoelectric element located between the first electrode and the second electrode. The actuator faces the pressure chamber. When a pulsating driving voltage is applied to the first electrode, an electrical field operates in the direction of the thickness on the piezoelectric element. The piezoelectric element that is being acted upon by the electrical field expands or contracts. The volume of the pressure chamber thus changes, and pressure (discharging energy) is applied to the ink within the pressure chamber.
Ink discharging characteristics may deteriorate when ink within the nozzle becomes more viscous, and unsatisfactory discharging may occur. In order to avoid this problem, discharge flushing may be performed to discharge the viscous ink from the nozzle.